The present invention relates to a camera with a strobe in which an amount of light emission can be changed.
In a conventional flashmatic system, photographing with a strobe has been carried out in the following manner: when a voltage of a capacitor for a strobe of the strobe unit is a predetermined value, charging for the capacitor is stopped so that an amount of strobe light emission becomes constant; and an amount of strobe light emission is adjusted by a diaphragm of a camera. This is due to the following reason: when the capacitor for a strobe of the strobe unit is charged to a predetermined voltage, and a period of time of strobe light emission is controlled, the relation between a period of time of strobe light emission and a guide number is absolutely determined. Accordingly, a control method, in which a period of time of strobe light emission is controlled so that light emission of a desired guide number can be obtained, is widely known.
Recently, a strobe light emission circuit in which a thyristor is replaced with an IGBT (Insulated Gate Bipolar Transistor) or the like, by which a period of time can be easily controlled, has been provided for the purpose of strobe light emission time control.
As described above, in the strobe unit in which an amount of strobe light emission can be controlled, for example, when the strobe unit, in which an amount of light emission can be changed, is used in the manner that it is combined with the diaphragm of the camera, the degree of freedom of photographic use is greater than a conventional constant amount of light emission.
In this case, for example, when flashmatic control is carried out, generally, an F-number table corresponding to the guide number is prepared, a subject distance is measured by a range finding means, and an amount of light emission is changed after a predetermined F-number has been found from the distance information by the measurement according to the F-number table.
However, when the guide number is changed two ways or more, capacity of a memory means in which the F-number table corresponding to the guide number is stored, is increased. Further, when a certain number of programs of a combination of the F-number with the guide number are programed, new tables are necessary.